Answer to Question #209983 in Physics for Tarik

Question

Consider as an example the image of a person 180 cm tall standing 2m from the eye. (a) Calculate the height of the full image at the retina. (b) Find the size of the face in the image and size of the nose. Suppose that the actual size of the persons face is 20 cm, and the nose size is one third of the face.

Answer 1

(a) $\frac{H}{d}=\frac{h}{d}\to \frac{1.8}{2}=\frac{h}{0.0171}\to h=0.01539\ (m)=15.39\ (mm)$

(b) The size of the face $\frac{0.2}{2}=\frac{h}{0.0171}\to h=0.00171\ (m)=1.71\ (mm)$

The size of the nose $\frac{(1/3)\cdot0.2}{2}=\frac{h}{0.0171}\to h=0.00057\ (m)=0.57\ (mm)$